Boat trailer



FIG. 1 is a perspective view of a boat trailer, showing my new design, wherein the tongue portion is shown in broken lines for illustrative purposes only and is not a part of the design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a side elevational view thereof; and

FIG. 5 is a rear elevational view thereof. 

The ornamental design for a boat trailer, substantially as shown and described. 